Compared with a conventional touch display device having a touch panel disposed on a Liquid Crystal Display (LCD) panel, a touch display device has become a mainstream of the touch display device technology. The touch display device, which integrated the touch panel and the LCD panel, has advantages of reduced usage of substrate and a smaller thickness. The touch display device integrating the touch panel and the LCD panel may have an on-cell structure or an in-cell structure. In the in-cell structure, a touch panel function is embedded in a TFT array substrate.
Nowadays, touch electrodes and common electrodes of a self-contained in-cell touch display are used in common. As shown in FIG. 1, the common electrode (com) is divided into a plurality of electrode blocks which are insulated from each other, and each of the plurality of electrode blocks is illustrated as a rectangular block E in FIG. 1. Each electrode block can be used, not only as a common electrode, but also a touch electrode. Each electrode block is connected with a signal transmission line S, which is adapted to provide the electrode block a common electrode signal and a touch detection signal.
However, in a TFT array substrate having the In-Cell touch panel, a parasitic capacitance between the signal transmission line and the common electrode is high, which results in a load of the TFT array substrate which is too large, a charging time of the touch electrode is long, and a touch sensitivity of the touch panel is reduced.